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b=M8Gdbgq0AtmVIRmA5CX6FLw146iXyBw5IUSNvl2Gt8xHJBpSBjNCLtyQSPiggsqSNKAMrZmSAA5J41eBq8ij/ASXF6aiGhGVlJO60WvWVLbnMrteMiPJCDWTfRKbmTyGArBjDseDHEqUMHYK1Iko7N/vZmVNdcWpBlyCvPdwemw= Authentication-Results: dkim=none (message not signed) header.d=none;dmarc=none action=none header.from=amd.com; Received: from BL3PR12MB9049.namprd12.prod.outlook.com (2603:10b6:208:3b8::21) by SA5PPF9D25F0C6D.namprd12.prod.outlook.com (2603:10b6:80f:fc04::8d9) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.21.71.12; Fri, 29 May 2026 00:29:52 +0000 Received: from BL3PR12MB9049.namprd12.prod.outlook.com ([fe80::ae6a:9bdd:af5b:e9ad]) by BL3PR12MB9049.namprd12.prod.outlook.com ([fe80::ae6a:9bdd:af5b:e9ad%6]) with mapi id 15.21.0071.011; Fri, 29 May 2026 00:29:52 +0000 Message-ID: <12e42f5e-95f7-4013-b96e-8241524f494f@amd.com> Date: Thu, 28 May 2026 19:29:48 -0500 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v5 2/7] x86/msr: add wrmsrq_on_cpus helper To: Borislav Petkov Cc: Dave Hansen , tglx@kernel.org, mingo@redhat.com, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, seanjc@google.com, peterz@infradead.org, thomas.lendacky@amd.com, herbert@gondor.apana.org.au, davem@davemloft.net, ardb@kernel.org, pbonzini@redhat.com, aik@amd.com, Michael.Roth@amd.com, KPrateek.Nayak@amd.com, Tycho.Andersen@amd.com, Nathan.Fontenot@amd.com, ackerleytng@google.com, jackyli@google.com, pgonda@google.com, rientjes@google.com, jacobhxu@google.com, xin@zytor.com, pawan.kumar.gupta@linux.intel.com, babu.moger@amd.com, dyoung@redhat.com, nikunj@amd.com, john.allen@amd.com, darwi@linutronix.de, linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org, kvm@vger.kernel.org, linux-coco@lists.linux.dev References: <20260527210603.GCahdcu8zvVjfKfGEL@fat_crate.local> <20260528004332.GDahePtGqVp2boiEJL@fat_crate.local> <2d164e19-5cc6-47ca-9150-f4d432dd10c4@amd.com> <3334a64a-9a5e-4ad5-94f3-01fef788df2e@amd.com> <20260529002613.GEahjdJRsX2uNz0GnH@fat_crate.local> Content-Language: en-US From: "Kalra, Ashish" In-Reply-To: <20260529002613.GEahjdJRsX2uNz0GnH@fat_crate.local> Content-Type: text/plain; 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>>> >>> I'm glad we're on the same page finally. I just hope we can get to this >>> point more quickly next time. I started off with exactly this >>> suggestion, but someone chimed in to the thread and said it was "slower": >>> >>>> https://lore.kernel.org/lkml/6a50d050-f602-43fd-a44a-cecedd9823eb@amd.com/ >>> >> >> Yes, actually i should have made it explicitly clear that we need to do it in >> parallel especially for issuing the RMPOPT instruction itself, as that is >> in a performance critical path (and for that we are using on_each_cpu_mask()). > > So which is it? Do we need the wrmsrq_on_cpus() helper or not? > > I'm confused. > No, we don't need it, i will drop this helper function patch. Thanks, Ashish